Clinical trial for patients failing checkpoint therapy uses combination of first-in-class, cryopreserved, CD16 NK cells, ImmunityBio’s IL-15 superagonist and checkpoint inhibitor Avelumab

EL SEGUNDO, Calif., March 19, 2020 – NantKwest, Inc. (Nasdaq: NK), a next generation, clinical-stage immunotherapy company focused on harnessing the unique power of our immune system using natural killer (NK) cells to treat cancer and infectious diseases, today announced dosing of the first patient in a Phase 2 trial for second- and third-line Merkel cell carcinoma (MCC) in patients who are refractory to immune checkpoint inhibitors. The trial will evaluate the Company’s first-in-class, off-the-shelf CD16-targeted natural killer (haNK) cells in combination with ImmunityBio’s IL-15 superagonist N-803 and Avelumab.

MCC is a rare and aggressive skin cancer that arises from uncontrolled growth of cells in the skin. Increasing in incidence, approximately 2,500 new cases are reported in the U.S. each year. Patients with metastatic or locally advanced MCC have an extremely poor prognosis, with less than 20% of patients surviving longer than five years. Typically, these patients are treated with a range of drugs, including chemotherapy, which can result in significant side effects. Although new immune therapies have the potential to improve survival, Merkel cell carcinoma is still fatal for a majority of patients who have progressed on or after treatment with a checkpoint inhibitor and represents an unmet medical need.

“With over 70% of patients failing checkpoint inhibitors in solid tumors, it is vital to develop novel and effective therapeutic options,” said Patrick Soon-Shiong, M.D., chairman and CEO of NantKwest and ImmunityBio. “Checkpoint and CAR-T therapies only target the T cell, which is a small portion of effector killer cells, and often result in substantial side effects. These side effects make those therapies unusable for many patients. Our combination therapy is designed to activate the innate immune system to create an immunological memory against tumors resulting in immunogenic cell death.”

“We have now established the first-in-class, cryopreserved CD16 NK-92 cell line, which can be manufactured under GMP conditions at scale. Having accomplished this development and manufacturing milestone in the field of NK cell therapy, we are actively pursuing pivotal trials for our CD16 NK-92 products haNK and PD-L1 t-haNK,” continued Soon-Shiong.

The single-arm study will involve 43 patients who failed all standard of care treatments for MCC, including checkpoint therapy (QUILT-3.063; NCT03853317). Clinical trial sites are currently being activated.

“Single-arm studies allow us to offer patients who have no other approved treatment options the opportunity to participate in a potential treatment for this rare and deadly disease without fear of receiving a placebo drug,” said John Lee, M.D., senior vice president of adult medical affairs at NantKwest. “Our past study using our non-targeted aNK cells showed clinical responses either alone or in combination with N-803. The current study builds on this approach using a PD-L1 antibody that will bind to the high affinity CD16 receptor on haNK cells to potentially help target PD-L1 tumor cells. The N-803 superagonist has been shown to enhance the body’s NK and T cells to also help attack the tumor cells. The goal of this work is to provide real hope for these patients using the power of our combination therapies.”

About NantKwest

NantKwest (NASDAQ: NK) is an innovative, clinical-stage immunotherapy company focused on harnessing the power of the innate immune system to treat cancer and virally induced infectious diseases. NantKwest is the leading producer of clinical dose forms of off-the-shelf Natural Killer (NK) cell therapies. The activated NK cell platform is designed to destroy cancer and virally infected cells from the body. The safety of NantKwest’s optimized, activated NK cells, as well as their activity against a broad range of cancers, have been tested in phase I clinical trials in Canada and Europe, as well as in multiple phase I and II clinical trials in the United States. By leveraging an integrated and extensive genomics and transcriptomics discovery and development engine, together with a pipeline of multiple, clinical-stage, immuno-oncology programs, NantKwest’s goal is to transform medicine by delivering living drugs in a bag and bringing novel NK cell-based therapies to routine clinical care. NantKwest is a member of the NantWorks ecosystem of companies. For more information, please visit www.nantkwest.com

haNK is a registered trademark of NantKwest, Inc.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include statements concerning or implying that NantKwest will be successful in improving the treatment of cancer. Risks and uncertainties related to this endeavor include, but are not limited to, obtaining FDA approval of NantKwest’s NK cells as well as other therapeutics as part of the NANT Cancer Vaccine platform as a cancer treatment.

Forward-looking statements are based on management’s current expectations and are subject to various risks and uncertainties that could cause actual results to differ materially and adversely from those expressed or implied by such forward-looking statements. Accordingly, these forward-looking statements do not constitute guarantees of future performance, and you are cautioned not to place undue reliance on these forward-looking statements.

These and other risks regarding NantKwest’s business are described in detail in its Securities and Exchange Commission filings, including in NantKwest’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2019. These forward-looking statements speak only as of the date hereof, and we disclaim any obligation to update these statements except as may be required by law.